Rocky Flats Closure Project (Site) includes several multi-year decontamination and decommissioning (D&D) projects which, over the next four years, will dismantle and demolish four major plutonium facilities, four major uranium facilities, and over 400 additional facilities of different types. The projects are currently generating large quantities of transuranic, low-level, mixed, hazardous, and sanitary wastes. A previous paper described the initial conceptual estimates and methods, and the evolution of these methods based on the actual results from the decommissioning of a 'pilot' facility. The waste estimating method that resulted from that work was used for the waste estimates incorporated into the current Site baseline. This paper discusses subsequent developments on the topic of waste estimating that have occurred since the baseline work. After several months of operation under the current Site baseline, an effort was initiated to either validate or identify improvements to the waste basis-of-estimate. Specific estimate and estimating method elements were identified for additional analysis based on the element's potential for error and the impact of that error on Site activities. The analysis took advantage of actual, more detailed data collected both from three years additional experience in decommissioning a second plutonium facility and from experience in deactivating certain non-plutonium facilities.